There are some Boinc projects which have Linux/ARM support. Just do a Ctrl-F on this list.

Also, some projects in that list (Milkyway@home, for example) have Android/ARM support even though there's no mention of it in that list. These are supported via NativeBoinc, an Android app with ARM optimized binaries. The list of supported projects can be found here, so maybe it's possible to roll your own Linux/ARM binary for these.

Bear in mind here that ARM processors are really, really, really, awfully slow. You won't make much of a hit in your stats with them!

The Tegra3 T30L in my Nexus 7 is a quad core A9 at 1.2-ish GHz - ARM gets faster, but not by much. It Linpacks at 150 GFLOPS from inside L2 cache, or about a quarter of what a 1.2 GHz Athlon can do (arbitrarily chosen, it's my oldest box which could theoretically boot). A fairly modern quad core should be passing 8,000 GFLOPs easily.